PRECISION OF ULTRASONIC ESTIMATES OF CHOROIDAL MELANOMA REGRESSION

Background: Important prognostic information may be gained from knowle dge of the volume and, over time, the change in volume of intraocular tumours such as choroidal melanomas. Methods: The precision and time c onsumption of three different ultrasonographic methods were evaluated. Seven choroidal melanomas were analysed after placement of a rutheniu m plaque and again after tumour regression had occurred. Perpendicular ultrasound B-scans were printed and analysed by overlay grid counting or outline tracing of tumour structures to calculate the volume. Thes e two methods, using only two perpendicular scans, were compared with a micro-computer-controlled ultrasonographic three-dimensional rotatio n scanning system, where each tumour was manually outlined in 20 revol ving scan planes. Results: The three-dimensional volume scanning metho d was the most precise, but also the most demanding in hardware and ti me consumption. Conclusion: Increased precision and less observer-depe ndent estimation of shrinkage rate after radiotherapy is available at the cost of sophisticated equipment.